Prenatal exposure to the phthalate DEHP impacts reproduction-related gene expression in the pituitary

Association of phthalate exposure with reproductive outcomes among infertile couples undergoing in vitro fertilization: A systematic review

Human fertility is impacted by changes in lifestyle and environmental deterioration. To increase human fertility, assisted reproductive technology (ART) has been extensively used around the globe. As early as 2009, the Endocrine Society released its first scientific statement on the potential adverse effects of environmental endocrine-disrupting chemicals (EDCs) on human health and disease development. Chemicals known as phthalates, frequently employed as plasticizers and additives, are common EDCs. Numerous studies have shown that phthalate metabolites in vivo exert estrogen-like or anti-androgenic effects in both humans and animals. They are associated with the progression of a range of diseases, most notably interference with the reproductive process, damage to the placenta, and the initiation of chronic diseases in adulthood. Phthalates are ingested by infertile couples in a variety of ways, including household products, diet, medical treatment, etc. Exposure to phthalates may exacerbate their infertility or poor ART outcomes, however, the available data on phthalate exposure and ART pregnancy outcomes are sparse and contradictory. Therefore, this review conducted a systematic evaluation of 16 papers related to phthalate exposure and ART pregnancy outcomes, to provide more aggregated results, and deepen our understanding of reproductive outcomes in infertile populations with phthalate exposure.

The Association between Autism Spectrum Disorder and Precocious Puberty: Considering Effect Modification by Sex and Neuropsychiatric Comorbidities

Limited knowledge is available about the association between autistic spectrum disorder (ASD) and precocious puberty. Our study examined the association between the two medical conditions and effect modification by sex and neuropsychiatric comorbidities in a nationwide population. To compare the risk of precocious puberty between ASD and non-ASD cases, we conducted a Cox regression analysis using ASD as the exposure and time to precocious puberty as the outcome. We adjusted for sex, attention-deficit/hyperactivity disorder (ADHD), tic disorder, obsessive-compulsive disorder (OCD), anxiety disorder, intellectual disability, and epilepsy. We performed a moderation analysis to examine the potential moderating effects of sex and comorbidities. Patients with ASD were prone to have precocious puberty, with an adjusted hazard ratio (aHR) of 1.80 (95% CI: 1.61-2.01). For effect modification, sex, specifically females, moderated the association between ASD and precocious puberty, with a relative excess risk due to interaction (RERI) of 7.35 (95% CI 4.90-9.80). No significant effect modification was found for any of the comorbidities within the scope of additive effect modification. We found that patients with ASD were prone to precocious puberty, regardless of sex or comorbid neuropsychiatric disorders. Girls with ASD are at a particularly higher risk of developing precocious puberty.

Influence of Ascorbic Acid on Di-(2-Ethylhexyl) Phthalate-induced Ovarian Gene Alterations in Pubertal Female Wistar Rats

Background

Di-(2-ethylhexyl) phthalate (DEHP), a plasticizer compound affecting female reproduction, leads to scenarios, such as polycystic ovarian syndrome (PCOS) and infertility through oxidative stress (OS) mechanisms. Ascorbic acid (AA) is one of the antioxidants in infertility issues.

Objectives

The present study investigates the ameliorative effect of AA on DEHP-induced ovarian toxicity in pubertal female Wistar rats.

Materials and Methods

Thirty female Wistar rats of four weeks of age were stratified into five groups. Group I was treated with corn oil (Vehicle), groups II and III with low and high dose DEHP, and groups IV and V with low and high dose DEHP+AA were administered for 30 days.

Results

Increased body weight gain was noted in DEHP groups. Estradiol hormone was considerably reduced, whereas progesterone levels were increased in both low- and high-dose DEHP-treated groups. DEHP+AA groups have shown significant ( p < 0.005) protection of these hormone levels as equal to the control group. The high-dose DEHP group shows an increased, ovarian estrogen receptor (ER) alpha, ER-beta, and progesterone receptor gene expression, and DEHP+AA groups have significantly ( p < 0.005) showed expression similar to the control. OS was noted with decreased superoxide dismutase and increased malondialdehyde expression in Group III (GR III) compared to control, whereas the DEHP+AA treated group significantly protected OS by restoring the expression levels. DEHP-treated groups show elevated levels of both Bcl-2 and BAX which is specific to apoptotic expression and restored by AA treatment ( p < 0.005).

Conclusion

Evidence suggests that AA may protect against DEHP-induced ovarian toxicity by decreasing OS levels, improving folliculogenesis, and restoring the hormonal with receptor level alterations.

Prenatal DEHP exposure induces lifelong testicular toxicity by continuously interfering with steroidogenic gene expression

Background

Epidemiologic studies suggested the association between prenatal di-(2-ethylhexyl) phthalate (DEHP) exposure and disorders of sex development (DSD), adult male disorders, and reproductive aging. Inhibiting testosterone synthesis by interfering with steroidogenic gene expression induces testicular toxicity, however, whether prenatal DEHP exposure induces testicular toxicity through this mechanism remains uncertain.

Methods

C57BL/6JGpt male mice underwent different doses (0, 100, 500, 1,000 mg/kg) of prenatal DEHP exposure during gestational day 10 to delivery day, the testicular toxicity (genital development, testosterone, semen quality, and morphology of testis tissue) in the neonatal, post-puberal and middle-aged stages was observed, and the steroidogenic gene (Lhcgr, Star, Cyp11a1, Cyp17a1, Hsd17b3, and Hsd3b2) expression was analyzed by quantitative polymerase chain reaction (qPCR) and Western blot (WB). The interference of steroidogenic gene expression in TM3 cells after mono-(2-ethylhexyl) phthalate (MEHP) exposure was also explored for verification.

Results

Prenatal DEHP exposure induced immediate testicular injury in the neonatal stage [reduced anogenital distance (AGD) and intratesticular testosterone], DSD in the post-puberal stage (poor genital development), and reproductive aging in the middle-aged stage (obesity, reduced testosterone and semen quality, and atrophic seminiferous tubules), especially in the high dose. Prenatal DEHP exposure continuously interfered with steroidogenic gene expression (Hsd3b2, Hsd17b3) in RNA and protein levels. MEHP inhibited testosterone synthesis of TM3 cells by interfering with steroidogenic gene expression (Hsd3b2, Hsd17b3) in RNA and protein levels.

Conclusions

Prenatal DEHP exposure induces lifelong testicular toxicity by continuously interfering with steroidogenic gene expression, thus indicating the association between prenatal exposure and DSD, adult male disorders, and reproductive aging.

Disruption of gonocyte development following neonatal exposure to di (2-ethylhexyl) phthalate

Pre- and/or post-natal administrations of di(2-ethylhexyl) phthalate (DEHP) in experimental animals cause alterations in the spermatogenesis. However, the mechanism by which DEHP affects fertility is unknown and could be through alterations in the survival and differentiation of the gonocytes. The aim of the present study was to evaluate the effect of a single administration of DEHP in newborn mice on gonocytic proliferation, differentiation and survival and its long-term effects on seminiferous epithelium and sperm quality. BALB/c mice distributed into Control and DEHP groups were used. Each animal in the DEHP group was given a single dose of 500 mg/Kg at birth. The animals were analyzed at 1, 2, 4, 6, 8, 10 and 70 days postpartum (dpp). Testicular tissues were processed for morphological analysis to determine the different types of gonocytes, differentiation index, seminiferous epithelial alterations, and immunoreactivity to Stra8, Pcna and Vimentin proteins. Long-term evaluation of the seminiferous epithelium and sperm quality were carried out at 70 dpp. The DEHP animal group presented gonocytic degeneration with delayed differentiation, causing a reduction in the population of spermatogonia (Stra8 +) in the cellular proliferation (Pcna+) and disorganization of Vimentin filaments. These events had long-term repercussions on the quality of the seminiferous epithelium and semen. Our study demonstrates that at birth, there is a period that the testes are extremely sensitive to DEHP exposure, which leads to gonocytic degeneration and delay in their differentiation. This situation can have long-term repercussions or permanent effects on the quality of the seminiferous epithelium and sperm parameters.

The effects of short-term and long-term phthalate exposures on ovarian follicle growth dynamics and hormone levels in female mice†

Di(2-ethylhexyl) phthalate and diisononyl phthalate are widely used as plasticizers in polyvinyl chloride products. Short-term exposures to phthalates affect hormone levels, ovarian follicle populations, and ovarian gene expression. However, limited data exist regarding the effects of long-term exposure to phthalates on reproductive functions. Thus, this study tested the hypothesis that short-term and long-term exposure to di(2-ethylhexyl) phthalate or diisononyl phthalate disrupts follicle dynamics, ovarian and pituitary gene expression, and hormone levels in female mice. Adult CD-1 female mice were exposed to vehicle, di(2-ethylhexyl) phthalate, or diisononyl phthalate (0.15 ppm, 1.5 ppm, or 1500 ppm) via the chow for 1 or 6 months. Short-term exposure to di(2-ethylhexyl) phthalate (0.15 ppm) and diisononyl phthalate (1.5 ppm) decreased serum follicle-stimulating hormone levels compared to control. Long-term exposure to di(2-ethylhexyl) phthalate and diisononyl phthalate (1500 ppm) increased the percentage of primordial follicles and decreased the percentages of preantral and antral follicles compared to control. Both phthalates increased follicle-stimulating hormone levels (di(2-ethylhexyl) phthalate at 1500 ppm; diisononyl phthalate at 1.5 ppm) and decreased luteinizing hormone levels (di(2-ethylhexyl) phthalate at 0.15 and 1.5 ppm; diisononyl phthalate at 1.5 ppm and 1500 ppm) compared to control. Furthermore, both phthalates altered the expression of pituitary gonadotropin subunit genes (Cga, Fshb, and Lhb) and a transcription factor (Nr5a1) that regulates gonadotropin synthesis. These data indicate that long-term exposure to di(2-ethylhexyl) phthalate and diisononyl phthalate alters follicle growth dynamics in the ovary and the expression of gonadotropin subunit genes in the pituitary and consequently luteinizing hormone and follicle-stimulating hormone synthesis.

Multi- and trans-generational effects of di-n-octyl phthalate on behavior, lifespan and reproduction of Caenorhabditis elegans through neural regulation and lipid metabolism

Di-n-octyl phthalate (DOP) is one important phthalate analog whose toxicities need comprehensive investigation to fully demonstrate phthalates health risks. In the present study, apical effects of DOP on behavior, lifespan and reproduction and the underlying mechanisms were explored in Caenorhabditis elegans for four consecutive generations (F1 to F4) and the trans-generational effects were also measured in the great-grand-children (T4 and T4') of F1 and F4. Multi-generational results showed that DOP caused both stimulation and inhibition on head swing, body bending, reverse, Omega steering, pharyngeal pump and satiety quiescence. The stimulation and inhibition altered over concentrations and across generations, and the alteration was the greatest in reverse locomotion which showed both concentration-dependent hormesis and trans-hormesis. DOP stimulated lifespan and inhibited reproduction, showing trade-off relationships. Significant trans-generational residual effects were found in T4 and T4' where the exposure was completed eliminated. Moreover, both similar and different effects were found in comparisons between F1 and F4, between F1 and T4, between F4 and T4' and also between T4 and T4'. Further analysis showed close connections between effects of DOP on neurotransmitters (including dopamine, acetylcholine, γ-aminobutyric acid and serotonin) and enzymes in lipid metabolism (including lipase, acetyl CoA carboxylase, fatty acid synthetase, carnitine palmitoyl-transferase, glycerol phosphate acyltransferase and acetyl CoA synthetase). Moreover, the close connections were also found between biochemical and apical effects. Notably, the connections were different in multi- and trans-generational effects, which urged further studies to reveal the response strategies underlying the exposure scenarios.

Di-2-ethylhexyl phthalate (DEHP) exposure induces sperm quality and functional defects in mice

Di-2-ethylhexyl phthalate (DEHP) harms mammalian testis development, yet the specific mechanism of its effect on sperm quality and function is unclear. In this study, male mice were administrated DEHP (200 mg/kg/day) via intragastric (i.g.) injection for 35 days. The sperm quality and function of DEHP-exposed mice were evaluated. DEHP exposure reduced the relative testis weight and serum testosterone levels. In addition, sperm count and motility parameters decreased significantly, which led to reduced sperm fertility characterized by reduced acrosome reaction rate, sperm-egg binding capacity and blastocyte formation. DEHP exposure decreased anti-oxidant indicators and the expressions of Cat, Sod1, Prdx6 and Sirt1 in the testis. DEHP-exposure also resulted in decreased proliferating cell nuclear antigen (PCNA) expression in mice testis, as well as the dose-dependent inhibition of the proliferation of GC-1 and GC-2 cells. These phenotypes may be related to increased cell apoptosis characterized by BAX/BCL2 and P53 up-regulation. DEHP exposure resulted in the down-regulation of SIRT1 and p-AKT in mice testis and decreased levels of GC-1and GC-2 cells. DEHP co-incubation with sperm in vitro resulted in decreased tyrosine phosphorylation and progressive motility, as well as p-AKT expression in capacitated sperm. Differential sperm proteomics identified 495 differentially expressed proteins, including 257 proteins down-regulated in the DEHP-exposure group. Bioinformatics analysis showed that proteins involved in sperm-egg interaction and fertilization processes were significantly down-regulated. Pathway analysis demonstrated that the adhesion pathway was enriched in down-regulated proteins, while the pathway associated with ribosomes was enriched in up-regulated proteins. Conclusively, DEHP exposure impaired male fertility by affecting sperm quality and function, and a pathway mediating the DEHP-induced decline in sperm quality and function was identified. The study provides additional information for understanding the molecular mechanisms of DEHP exposure and its effects on male reproduction.

Subchronic exposure to environmentally relevant concentrations of di-(2-ethylhexyl) phthalate differentially affects the colon and ileum in adult female mice

Di(2-ethylhexyl) phthalate (DEHP) is a large-molecular-weight phthalate added to plastics to impart versatile properties. DEHP can be found in medical equipment and devices, food containers, building materials, and children's toys. Although DEHP exposure occurs most commonly by ingesting contaminated foods in the majority of the population, its effects on the gastrointestinal tract have not been well studied. Therefore, we analyzed the effects of subchronic exposure to DEHP on the ileum and colon morphology, gene expression, and immune microenvironment. Adult C57BL/6 female mice were orally dosed with corn oil (control, n = 7) or DEHP (0.02, 0.2, or 30 mg/kg, n = 7/treatment dose) for 30-34 days. Mice were euthanized during diestrus, and colon and ileum tissues were collected for RT-qPCR and immunohistochemistry. Subchronic DEHP exposure in the ileum altered the expression of several immune-mediating factors (Muc1, Lyz1, Cldn1) and cell viability factors (Bcl2 and Aifm1). Similarly, DEHP exposure in the colon impacted the gene expression of factors involved in mediating immune responses (Muc3a, Zo2, Ocln, Il6, and Il17a); and also altered the expression of cell viability factors (Ki67, Bcl2, Cdk4, and Aifm1) as well as a specialized epithelial cell marker (Vil1). Immunohistochemical analysis of the ileum showed DEHP increased expression of VIL1, CLDN1, and TNF and decreased number of T-cells in the villi. Histological analysis of the colon showed DEHP altered morphology and reduced cell proliferation. Moreover, in the colon, DEHP increased the expression of MUC2, MUC1, VIL1, CLDN1, and TNF. DEHP also increased the number of T-cells and Type 2 immune cells in the colon. These data suggest that subchronic DEHP exposure differentially affects the ileum and colon and alters colonic morphology and the intestinal immune microenvironment. These results have important implications for understanding the effects of DEHP on the gastrointestinal system.